How do I set a specific render engine while launching blender?
Yes, it is possible.

There are lots of command-line flags provided by Blender and the flags that are related to rendering engine type are -E engine or --engine engine

So, to launch Blender with the CYCLES rendering engine set, the following command can be used.

blender --engine CYCLES


You can get a list of available engines by using

blender --engine help


or

blender -E help


Example output

found bundled python: /home/satishg/bin/blender-2.65a-linux-glibc27-x86_64/2.65/python
Blender Engine Listing:
    BLENDER_RENDER
    BLENDER_GAME
    CYCLES

[1]    Done                          ~/bin/blender-2.65a-linux-glibc27-x86_64/blender --engine help